This NMA will follow the PRISMA guidelines extension for NMA (see additional file 1) (15). This protocol has been registered with PROSERO (ID CRD42023429618). The report in PROSPERO will be updated with any required amendments.
Characteristics of studies
All prospective comparative studies comparing active antibiotics, or to placebo or no antibiotic in patients undergoing surgery following hand and/or wrist trauma will be included. Both randomised and non-randomised trials will be included.
Characteristics of participants
Participants of all ages undergoing hand and or wrist surgery for traumatic injuries within two weeks of their injury will be included. Participants with elective operations will be excluded. There will be no restrictions in terms of gender, ethnicity, comorbidities, mode of injury, contamination status, injury severity and time of presentation.
Interventions
All antibiotics in oral or injectable form used within its licensed therapeutic dosages will be included. Antibiotics will be grouped based on their classes i.e. macrolides, penicillins, cephalosporins reflecting their mechanism of action. Both oral, IM and IV forms will be grouped together due to their common short acting nature. Placebo and no antibiotic use will be grouped due to the anticipated lack of placebo effect on SSI development. It has been hypothesised that antibiotics should be given 30-60 minutes before surgery to allow tissue concentration to reach therapeutic levels at the time of operation. (16) We will thereby assess the effect of the timing of antibiotic use (pre-, intra-, post-operative) with further subgroup analyses.
Outcome measures
The primary outcome investigated will be a dichotomous outcome assessing the development of surgical site infection within 30 days of the operation or within 90 days if a prosthetic material is implanted (as defined by the CDC). (17) SSI diagnosis by any method will be included and its definition outlined in a descriptive table.
Search strategy and study selection
The electronic databases EMBASE, MEDLINE, CINAHL and CENTRAL will be searched for published comparative studies. The electronic search will be supplemented by a manual search for unpublished and ongoing comparative studies in the metaRegister of controlled trials, clinicaltrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) for unpublished data to reduce publication and reporting bias. We will use CitationChaser to perform forward and backwards citation chasing (18). We will include all studies irrespective of their country of origin or language. Two persons will independently review references and abstracts retrieved by the search to identify eligible studies. Disagreements will be resolved via a discussion with a third member and a study attrition chart will be used to present the outcomes of the search strategy and subsequent screening process.
Data extraction
Data will be extracted from the eligible studies and cross-checked for data discrepancies by a second reviewer. Information extracted will include:
- General study characteristics (e.g. author, publication year, study type)
- Methodology information (e.g. duration, blinding, randomisation, SSI criteria)
- Participant characteristics (e.g. age, co-morbidities, gender)
- Injury characteristics (e.g. type of injury, operation performed)
- Antibiotic characteristics (dose, mode, type, timing of use)
- Outcome measures
The dichotomous primary outcome of SSI will be recorded in the outcome measures section descriptively and as a proportion of overall study population. As symptoms of SSIs typically occur 3-7 days post-surgery (19) follow up in the acute period post-surgery will be deemed sufficient and complete follow up to 30 days (or 90 days in implanted devices) will not be required. Loss to follow up can be due to a lack of post-operative complication or follow up and treatment in community setting thereby causing difficulty in the interpretation of missing data. Outcomes of patients who do not attend follow up or leave the study early will thus be excluded from the study via a per protocol analysis.
We anticipate a high variability of definition and determination of SSI as this is a subjective outcome which will be dependent on factors such whether this is reported by a clinician or self-reported by the patient or whether an in-person clinical examination is conducted compared to telephone questionnaires. There will also be variability on other wound management techniques such as irrigation and anti-septic cleaning. These details will be collated from the papers published and presented in a descriptive table.
Risk of bias assessment
The risk of bias will be evaluated in the following domains: allocation sequence, allocation concealment, blinding of participants and study personnel, blinding of outcome assessment attrition, selective reporting and other domains including sponsorship bias. The risk of bias of RCTs will be assessed using the Cochrane ROB-2 tool (20) and non-randomised studies will be assessed with the ROBIN-I tool (21). The risk of bias due to missing evidence will be assessed using the ROB-MEN tool (22). A random 20% of studies will be checked independently by a second reviewer for consistencies.
Data analysis
Transitivity is the fundamental assumption of NMAs and will be investigated carefully as treatments cannot be jointly analysed if the network is intransitive (23). We assume that patients who fulfil the inclusion criteria are equally likely to receive any of the antibiotic treatments we are planning to compare. Clinical characteristics which have not been shown to affect infection development in hand surgery include location of operation (24), time to surgery (25), depth and extent of injury (26) and diabetes (9). We will investigate age, injury location and type with regards to its distribution between the studies. If the collected studies appear to be sufficiently similar with respect to the distribution of effect modifiers we will proceed to NMA.
We will produce a network plot to summarise the interventions followed by a series of frequentist, random-effects NMAs using the netmeta package in R assuming a single heterogeneity parameter (27).
To assess the agreement between randomised and non-randomised studies, we will perform separate NMAs and compare the results (28). This will be supplemented by a series of “designed-adjusted analyses”, whereby data from randomised studies will be combined with down-weighted data from non-randomised studies (NRS) using the following variance inflation factors: w=1 (corresponding to the naïve NMA, i.e. all studies at face value), 0.8, 0.6, 0.4, 0.2 and 0 (i.e. zero excludes NRS). These will be displayed as forest-plots per treatments against the reference. If no discrepancies are observed in any of these analyses, we will proceed to joint (“naïve”) analysis pooling both randomised and non-randomised data as the primary analysis.
Interventions will be ranked by their P-scores using the netrank function; P-scores are assumed to take a value between 0 and 1, with a higher score indicating a better treatment (29). With the netleague package, we will generate league tables with the intervention efficacy ordered by P-score. Forest plots of relative risks (RR) and 95% confidence intervals (CI) will be generated with placebo as the reference treatment. Heterogeneity will be quantified through the standard deviation of random effects (τ, assumed common for all comparisons). To assess inconsistency, we will use both global and local methods with the netsplit package (30), (31) and display the findings via heat plots using the netheat command (32). In case of inconsistency we will investigate for possible sources and if appropriate, further explored by network meta-regression and subgroup analyses.
Given that SSI is rare, we will perform sensitivity fixed-effects Mantel-Haenszel NMA (33) using the netmetabin package and inconsistency will be assessed using the netsplit package and SIDDE approach.
Network meta-regressions or subgroup analyses will be used to investigate the impact of (a) injury type (b) operation type (c) antibiotic timing. There will likely be heterogeneity and inconsistency due to the wide range of study settings and the relatively small sample size. We anticipate that there may be heterogeneity resulting from differing bacterial flora on the hand due to the location of the study, thereby affecting bacterial susceptibility profiles. Thus the sensitivity of the conclusion will be evaluated by analysing studies at low risk of bias and the location of the study.
We will explore the confidence in estimates of the conclusion with be evaluated with the Confidence in networked meta-analysis (CINeMA) framework which considers the six domains within-study bias, reporting bias, indirectness, heterogeneity, incoherence and imprecision (34).
To estimate the overall prevalence of SSI, we will use the R package metaprop (35) with Hartung-Knapp-Sidik-Jonkman random-effects and the Freeman-Tukey double arcsine transformation to stabilise the variances.
The relationship between study size and effect size (also known as small study effects) will be explored with a comparison-adjusted funnel plot.